The basic structure of the common fluorescent lamp socket for reception of a pair of bayonet pins is well-known because such sockets are in wide-spread use. Two prior art patents which disclose devices of this particular nature are U.S. Pat. Nos. 2,295,575 and 2,767,349. The latter of these two patents also discloses the adaptation of the socket for use with a third electrical contact to provide a so-called disconnect arrangement to achieve certain safety measures.
The invention herein obviates or substantially decreases the need for disconnect sockets but can be applied to disconnect sockets for added safety.
The ordinary socket in its frontal aspect, i.e., facing the lamp, presents a circular recess which has a lateral entrance or guide passageway leading to the interior of the face of the socket alongside of the recess so that both pins enter to the interior from one side of the circular recess through the guide passageway. When the pins are moved transverse of the circular recess there is a central peg coaxial with the recess split up its center and integral with the back wall of the socket housing to define a pin channel extending diametrically across the recess. When fully aligned with the recess the pins may be rotated either way to make contact.
The electrical contacts present facing V-shaped resilient contact arms on opposite sides of the circular recess, the pins adapted to be led into engagement with the respective ends of these arms during insertion of the lamp after which the detent effect leads the pins to the bights as the lamp is rotated, one entering a bight from the top of the recess and the other entering its bight from the bottom of the recess.
One of the problems with the ordinary fluorescent lamp socket is that when a pair of the fluorescent lamp pins is inserted into the front of the socket it requires very little movement, i.e. rotation of the pins to establish engagement with the contacts so that it is possible for the contacts to be established at one end of the lamp in its socket without actually seating the pins at the opposite end of the lamp in that socket.
According to the invention the socket is constructed so that the electric contacts are located at the ends of respective arcuate passageways or channels, the channels beginning at the pin entrance alongside the circular recess and extending in a generally pinwheel relation with one another to the dead ends of the channels. It is only when the pins have been rotated about 135.degree. that contact can be made between pins and contacts so that the chances of electrical engagement between the pins and the contacts of the socket are otherwise very little. This not only holds true for each socket but as well holds true in that the lamp must have both pair of pins seated before electrical engagement is likely to occur.
This means that electrical shock is unlikely even if a service man holds one end of a lamp and attempts to insert the other end in a socket. Where there is a disconnect contact to be engaged, the chances of a shock occurring are even less.
The sockets of the invention are not symmetrical; hence they are required to be formed as matching right and left sockets for each pair and must be properly mounted. It will also be noted that unlike the conventional sockets the lamp must be rotated in only one direction to achieve electrical engagement between pins and contacts. The construction prevents rotation in an improper direction.